docs: def _compute_distance(cls, dists, coeffs):
          """
          Compute third term of equation (1) on p. 1200:
  
          ``b3 * log(sqrt(Rjb ** 2 + b4 ** 2))``
          """
          return coeffs['b3']*np.log10(np.sqrt(dists.rjb**2. + coeffs['b4']**2.))